The Space Shuttle Program objective is to establish a national space transportation capability that will substantially reduce the cost of space operations and support a wide range of scientific, defense, and commerical uses. The Space Shuttle Program has successfully completed its first phase-the Approach and Landing Test (ALT) Program. Testing is currently underway on all major components of the ...
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During space flight, the communications and tracking system of the Space Shuttle Orbiter usesS-band andKu-band links to provide, in addition to tracking, reception of digitized voice, commands, and printed or diagrammatic data at a maximum rate of 216 kbits/s. The system provides a transmission capability for digitized voice, telemetry, television, and data at a maximum rate ...
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NASA presently maintains a worldwide system of ground tracking stations to provide communication support (tracking, telemetry and command) to all authorized user spacecraft missions. The set of ground stations supporting Earth orbiting missions, and their supporting communication links (called NASCOM) to various NASA centers, is designated as the Spaceflight Tracking and Data Network (STDN). Major...
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This paper discusses the role of radio navigation and communications equipment for Space Shuttle navigation. Radio navigation systems are discussed in terms of their ability to support Space Shuttle flight operations. A phased development of navigation capability from conventional trackers to relay satellites and navigation satellites is reviewed.
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The salient performance parameters of the black boxes used to form the ShuttleS-band system are summarized. Included are functional descriptions as well as design capabilities and limitations. Some of the design problems which were encountered are discussed and the subsequent actions to resolve them. The available operating modes for each box and integration with the totalS-b...
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The purpose of this paper is to present a theory which can be used to determine the effects which phase noise sources produce on the bit error probability performance of phase coherent links. The paper begins by presenting typical math models for phase noise sources known to exist in frequency generators. These phase and frequency instability models are then incorporated into equivalent loop model...
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When a Costas loop is operated in a PM mode, such as on the Space Shuttle OrbiterS-band uplink during the time when both data and a ranging subcarrier are linearly modulated on the carrier, and if the data modulation index is less thanpi/2, the loop must reconstruct its carrier reference from an input signal whose carrier component is not completely suppressed. This paper est...
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A solution to the mean time to lose lock for a first order, pseudo-noise, code tracking loop is derived for both the fulltime delay-lock loop and the time-shared delay lock loop, with both utilizing an early-late gate size of 1/2 chip, and assuming ideal bandpass filters. The result allows a spread spectrum system designer to assess the slip time performance of his code tracking loop by a simple c...
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This paper provides an overview of the various classes of candidate payloads to be flown on early Shuttle missions and summarizes the communications and data handling services which the Space Shuttle will provide for payloads. The Space Shuttle system mission capabilities are briefly described and data processing capabilities for payload support are discussed for the various classes of payloads.
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This paper describes the Spacelab command and data management system for both the manned-module and pallet-only configurations. The Spacelab support capabilities for various types of experiments are described in terms of data processing, display, recording and multiplexing. The Spacelab's utilization of Orbiter data processing and data transmission capabilities is also discussed.
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One mission of the Shuttle is to place payloads into Earth orbit or on escape trajectories and to recover payloads from Earth orbit. In order to properly deploy and retrieve such payloads, operational and diagnostic communications must take place between the payloads and the Shuttle. The results of such communications, in the form of tracking, commands, and telemetry, will be interpreted both aboa...
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An example of the growing influence of the microprocessor in communications is illustrated in this description of the payload bit synchronizer and other related payload signal processing functions for the Space Shuttle. Stored in firmware the microprogrammed control at 2.56 M-instructions/s accomplishes bit synchronization, matched filter detection, NRZ-Lconversion and frame synchroniza...
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TheKuband subsystem for the NASA Space Shuttle Orbiter operates either as a radar system during rendezvous with other space vehicles or as a two-way communications system with the ground through the Tracking and Data Relay Satellite System (TDRSS). In its radar function the equipment searches for, acquires, tracks, and provides the spatial data needed to make a quick and efficient rende...
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The performance of a class of pulse Doppler radars with a digitally implemented signal processing unit is investigated. TheKuband rendezvous radar onboard the Shuttle Orbiter is a pulse Doppler radar which is in this class. The detection capability is first presented. A unified analysis of digital radar tracking loops is presented which employs logarithmic discriminants. The results are...
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The design and implementation of a multiplexed 50 Mbit/s convolutional encoder/decoder system is described. An implementation strategy utilizing multiple medium speed Viterbi decoders is presented, along with test equipment used to simulate a complete coded communications system.
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This paper systematically analyzes the signal-signal-to-noise ratio degradations which can potentially occur due to data asymmetry in digital transmission systems. Suitable asymmetry models are developed and error probability performance for various types of data detectors (integrate-and-dump filter, filter-sample detector, and gated-integrate-and-dump filter) is derived. Although this work was do...
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Two algorithms for voice encoding are described. One, the modified Abate, is a simplified version that is the type designed for the Space Shuttle. Waveforms of the response of the delta modulators to channel errors are given and performance data that shows the relationship between channel errors and word intelligibility are included. An analytic derivation yielding a comparison between PCM and ada...
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Shuttle voice processing uses a Variable Slope Delta Modulation scheme which is a variant of the ABATE algorithm. This paper summarizes the ground terminal subsystem which processes the multiplexed voice and telemetry data digital sequence in the downlink processing and digitizes the voice signal in the uplink processing. The Delta Modulation System (DMS) performance characteristics are given in t...
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The Space Shuttle initially will be using a field-sequential color television system but it is possible that an NTSC color TV system may be used for future missions. In addition to downlink color TV transmission via analog FM links, the Shuttle will use a high resolution slow-scan monochrome system for uplink transmission of text and graphics information. This paper discusses the characteristics o...
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The spread spectrum acquisition and tracking performance for the ShuttleS-band andKu-band communication links are analyzed and compared to test results. TheS-band link requirements are more severe than those of theKu-band links, hence, different despreader designs were developed for the two systems. TheS-band despreader acquires pseudonoise co...
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The false (sideband) lock problem in Shuttle Costas loop receivers, in the presencse of noise, is assessed in this paper. False lock margin is defined depending on symbol signal-to-noise ratio rather than in the absence of noise as reported earlier in [4], [5]. Closed form results are given when the arm filters of the Costas loop are one-pole Butterworth filters as used in the Shuttle receivers. H...
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The selection, design and development of the Orbiter antenna subsystem described herein gives some insight into the problems and solutions encountered on the Orbiter vehicle design. The uniqueness of the Orbiter spacecraft, in terms of being both a spacecraft and airborne vehicle, designed for multiple flights with little or no refurbishment between missions, required a state-of-the-art developmen...
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